The present invention relates to an article handling method for an in-line manufacturing process. More specifically, the invention is especially useful for transferring delicate materials such as hydrated contact lenses, for example, between separate manufacture processing steps.
Small, delicate work pieces such as contact lenses are difficult to transfer through multiple stages of a manufacturing process. In the dry state, a contact lens is fragile and prone to scratching, cracking and breaking. In a hydrated state, a contact lens tears easily and is difficult to handle as the lens is extremely pliable. Manipulating a contact lens into a desired orientation, such as having the concave side of the lens facing upward or toward a particular direction, can be difficult. Usually, this orientation must be done manually and requires a laborious process, often involving human effort. A worker may have to turn the lens with a pair of tweezers. Inevitably, whether the lens is dry or hydrated, the tweezers damage the lens. The worker may also be exposed to repetitive motions, contributing to injuries. It has therefore been desirable to automate as much of the contact lens manufacturing process as possible.
At certain stages of the manufacturing process, the lens is dry. U.S. Pat. No. 5,969,793 (Dobner, assigned to Bausch & Lomb Incorporated) discloses a method and apparatus for transferring a dry lens between different stages of a manufacturing process. The lens remains centered during the transfer. Once the lens is transferred to a support, it can now undergo processing such as edging which requires the lens to be centered.
U.S. Pat. No. 5,503,515 (Moorehead, assigned to Bausch & Lomb Incorporated) discloses an apparatus and method for inverting contact lenses while on a tray. The tray includes a plurality of small, spaced perforations having diameters substantially smaller than any one of the lenses. A plurality of lenses are placed convex side-up on the tray such that the lenses are positioned over at least one perforation. A source of air is located below the tray and directs a stream of air upwardly so as to invert the lenses, resulting in concave side-up lenses.
After hydration, handling or transferring a wet contact lens presents additional technical problems. It is perhaps even more difficult to manipulate a wet soft contact lens than a dry lens in an automated fashion.
U.S. Pat. No. 5,561,970 (Edie et al.) discloses a robotic lens transfer device which utilizes vacuum within an effector end having a transfer tip. The transfer tip has a series of bore openings which are radially oriented. The transfer tip is positioned over a hydration cup and a vacuum is applied prior to lens pickup. The tip is lowered into close proximity to the lens and the lens is picked up from the mold. The tip is then positioned over a blister package and by applying air blow-off, the lens is deposited into the package. The lens as placed in the package is in the original orientation as it was in the hydration cup.
Some mold parts are utilized as part of the packaging. For example, U.S. Pat. Nos. 5,143,660 and 5,573,108 (both to Hamilton et al.) discloses a contact lens package comprising a mold part. The lens is cast between a male mold surface in a first mold part and a female mold surface in a second mold part. The mold is opened to expose the cast lens while supported on the male mold surface. The lens is sealed in a package by sealing a cover member onto first mold part. These types of process require little manipulation of lens.